Which of the following substances can act as a Bronsted acid in aqueous solution? (Select all that apply.)
C3H8
NH41+
HCl
H2
H2O
H2CO3
PH3
Which of the following substances can act as a Bronsted base in aqueous solution? (Select all that apply.)
PH3
PH41+
CO32-
SO42-
H2
CH4
NH3

If the substance can donate a proton, it is a Bronsted acid. If it can accept a proton, it is a Bronsted base.
examples:
Bronsted acid. HCl or NH4^+
HCl + H2O ==> H3O^+ + Cl^-
NH4^+ + H2O ==> H3O^+ + NH3